title: A component of gamma-radiation-induced cell death in E. coli is programmed and interlinked with activation of caspase-3 and SOS response.
abstract: The current study deals with the molecular mechanism of radiation-induced cell death (RICD) in Escherichia coli. Irradiated E. coli cells displayed markers similar to those found in eukaryotic programmed cell death (PCD) such as caspase-3 activation and phosphatidylserine externalization. RICD was found to be suppressed upon pretreatment with sublethal concentrations of rifampicin or chloramphenicol, indicating the requirement of de novo gene expression. RICD was also found to be inhibited by cell permeable inhibitors of caspase-3 or poly (ADP-ribose) polymerase, indicating the involvement of PCD during RICD in E. coli. Radiation-induced SOS response was alleviated as observed with decrease in LexA level and also reduced cell filamentation frequency in the presence of caspase inhibitor. Further, the inhibitor-mediated rescue was not observed in single-gene knockouts of umuC, umuD, recB and ruvA, the genes which are associated with SOS response. This implies a linkage between SOS response and PCD in radiation-exposed E. coli cells.
authors.affiliation: Food Technology Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
authors.forename: Surbhi
authors.initials: S
authors.lastname: Wadhawan
authors.forename: Satyendra
authors.initials: S
authors.lastname: Gautam
authors.forename: Arun
authors.initials: A
authors.lastname: Sharma
mesh_terms: D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism*; D061945:Caspase Inhibitors / Q000494:pharmacology; D016923:Cell Death; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005720:Gamma Rays; D015870:Gene Expression / Q000187:drug effects; D050296:Microbial Viability; D013014:SOS Response, Genetics / Q000187:drug effects
chemical_list: D061945:Caspase Inhibitors; D029968:Escherichia coli Proteins; D053148:Caspase 3